Alta Mar (High Seas)

Alta Mar (High Seas) delivers the most gripping mystery of any Netflix Spanish series set before 1970. Set aboard a luxurious ocean liner in the 1940s, the show plunges two sisters into a web of dark secrets and murders on a voyage from Spain to Brazil. With over 80% of scenes shot on meticulously recreated period decks, the production design outshines #2's era-specific sets in depth and authenticity. Compared to Intimidad, Alta Mar offers a slower-burn narrative but compensates with twisty plotting that keeps viewers guessing until the final episode.